Electron tube



Jan..l4, 1947. H. BRANsoN 2,414,137

ELEcTRoN TUBE Filed Feb. 29, 1944 Zh@ 6&7 f

Patented Jan. 14, 1947 ELECTRON TUBE Harry Branson, Hightstown, N J.,assignor, by A mesne assignments, to Philco Corporation, Philadelphia,Pa., a corporation of Pennsylvania Application February 29, 1944, SerialNo.524,415

Claims. (Cl. Z50-27.5)

'I'his Iinvention relates to space discharge-de vices, such as vacuumtubes,` and is especiallyV concerned with the construction of the tubeelements and the conducting leads therefor.

A critical, predetermined spatial relationship must be maintainedbetween the electrodes of vacuum tubes, and the flexibility andrelatively small diameter of the electrode supporting members commonlyemployed heretofore have resulted in substantial problems duringmanufacture. is understood that it is common to support and space theelements during the manufacturing process by gripping that portion ofthe support members which projects' outwardly of the envelope area; andthat it has proved extremely difficult to maintain the criticalrelationship between the tube elements, due to the flexibility Vof thewire leads supporting them and their consequent susceptibility tovibration and displacement.

Accordingly, it is a primary object of the present invention to providea vacuum tube de- The difficulties will be apparent when it 1 vicehaving rigid supporting-conducting leads'of a novel character whichpermit positive retention of the tube elements in precise spacing andalignment, during the manufacture of the tube.

More particularly, the invention contemplates `the provision of rigidmetal sleeves adapted to trode leads are of unusually large diameter,

thereby resulting in relatively low lead inductance. It is also anobject of the invention to provide'a vacuum tube in which the leads areconveniently disposed and adapted for connection to external circuits.

A further object relates to the provision of a vacuum tube having anindirectly heated cath-- ode, in which the heater circuit is Wellshielded from the radio frequency circuit.

Broadly, it is an object of the invention to provide a vacuum tube whichis susceptible of extremely simple and inexpensive manufacture.

It is a more particular object of the invention to provide a vacuumtube'- having rigid generally.

cylindrical sleeve-like leads which are readily adaptable to jigassembly.

'I'he invention also contemplates the provision of a vacuum tube havinga novel getter arrangement, by means of which it is possible to localizethe getter deposit in an area removed from the insulating envelope.

A further object of the invention resides in the provision of a .vacuumtube in which the exhaust tubulation is simplified.

These and other objects and advantages of the invention will be bestunderstood by making reference tothe following description takentogether with the accompanying drawing, in which:

Fig. 1 is an enlarged sectional view of a vacuum tube constructed inaccordance with the present invention, the illustration showing the tubetipped up from its normal position, 'the getter cup Il being secured tomember 6 by welding or other appropriate means; and

Fig. 2 is a plan view of one Vof the tube ele-l ments and the mountingtherefor.

Referring more particularly to the drawing, there is illustrated avacuum tube which comprises, generally, a glass envelope 3, spaced anodeand cathode elements 4 and 5, respectively, ,and cylindrical metalsleeves 6 and 1, adapted to support said cathode and anode elements; andto serve Vas conducting leads. The sleeves are preferably formed ofKovar (the thermal coefficient of expansion of this material beingsubstantially equal to that of the glass commonly employed) and aresealed into opposed walls of the envelope as shown at 8 and 9. Althoughthe invention is not limited to vacuum tube devices in which the tubeelements are arranged in confronting relation, as shown, such isdesirable by reason of the reduction in lead capacitance. Similarly, itwill be understood that the invention is also useful with tubes of otherthan the diode type, although the description isy limited to such typesin the interests of clarity.

The anode and cathode elements 4 and 5 are supported Within the sleeves6 and 1 by means of small strap members l0, preferably of Nichrome,which, as best seen in Fig. 2, may be secured to the free end of thesleeve structure, as by butt welding or the like. The inner ends ofthese straps are provided with upwardly turned flange portions l5 whichare secured (as by welding) to the outer lcylindrical surface of theanode and cathode elements. It will be understood that the face of thecathode element incorporates a suitably treated surface and, asillustrated, thel cathode is indirectly heated by the resistance elementshown schematically at ll. The vcylindrical sleeves project outwardly ofthe envelope a distance suilclent to permit their ducting sleeveengagement with a suitable iig, during the manufacturing operation, andhave their outside ends sealed with an exhaust tubulation I2. Connectionto the sleeves may be accomplished in any desired manner. Y

As is well understood, high frequency currents applied to theanode-cathode circuit of the diode will tend to travel along the outersurface of the sleeves 6 and l, and this fact has been utilized to keepsuch high frequency currents out of the heater filament circuit. Suchshielding of the filament circuit in high frequency applications isextremely desirable, since any induced current in the filament circuitreduces the efficiency of the tube. Moreover, the sleeve 6 functions asa shield structure to shield the diode circuits from the magnetic fieldabout the heater wires Il.

A feature of the improved construction resides in the location of lthegetter cup lIl withinthe sleeve 6. When the getter is fired, the depositof getter material is localized within the conducting sleeve, therebypreventing any reduction of the Y insulating qualities of the envelope.

While the device hasbeen illustrated on a greatly enlarged scale, itshould be understood that the construction lends itself well to themanufacture of extremely small and compact vacuum tubes, for example,tubes in which the greatest dimension of the envelope may not be greaterthan 1/2-inch; the diameter of the con- Vbeing in the neighborhood of1Affinch.

In constructing the tube, the anode and cathode elements are firstsuitably positioned within and secured to the sleeves 6 and l, afterwhich the outer ends of said sleeves may be positioned in a supportingjig and the distance between the cathode and anode elements iixedlyestablished. Following this, the glass envelope is applied to theassembly, being sealed to the sleeve members as by glass welding. Thetube is then evacuated and the exhaust tubulation accomplished in anymanner which may prove convenient to one skilled in this art, nolead-supporting. pinch being necessary.

From the foregoing description it will be evident that the inventionprovides a. vacuum tube which is susceptible of precise fabrication byextremely simple and inexpensive manufacturing methods. In addition tothe manufacturing advantages set forth above, the compact rigidconstruction of the tube improves the performance thereof by th'evirtual elimination of vibration of the tube elements and consequentmicrophonics.

In additionthe device of the present invention is susceptible of wideuseage, by reason of its ruggedness vand its adaptability for use with avariety of external circuits. For example, the rigid sleeve-like leadsmay be readily inserted Within adjacent portions of the internalconductor of a coaxial transmission line.

While a particular embodiment of the invention has been illustrated anddescribed, it should be understood that the invention, in the broadestaspect, is not limited thereto. For example, while hollow cylindricalmembers are employed, certain advantages of the invention may berealized by the utilization of solid rod-like members of sufiicientdiameter to impart the desired degree of rigidity. With such anarrangement a directly heated cathode might be utilized. However, itwill be apparent that the invention is susceptible of certain changesand modiiications Within the scope of the appended claims.

I claim: 1

1. Ina space discharge device incorporating at least diode elements, anenvelope formed of insulating material and having opposed walls withaligned aperatures therein, a pair of rigid conductive tubular membersprojecting through said apertures into said envelope and being sealed tosaid walls withftheir longitudinal axes in substantial alignment, saidmembers having-their inner ends in predetermined spaced relation withinsaid envelope and having their outer end portions extending asubstantial distance outside .the envelope, anode and cathode elementshaving substantially plane surfaces supported upon the respective innerends of said members in substantially perpendicular relationto thelongitudinal axes of said members, and means sealing the outer ends ofsaid members.

2. In a space discharge device incorporating at least diode elements,anenvelope formed of insulating material and having opposed walls withaligned apertures therein, a pair of rigid conductive tubular membersprojecting through said apertures into said 4envelope and being sealedto` said walls with their longitudinal axes in substantial alignment,said members havlng'their inner ends in predetermined spaced relationwithin said envelope and having their outer end portions extending asubstantial distance outside the envelope, anode and cathode elementssupported u-pon the 4respective inner ends of said members, meanssealing the outer ends of said members, and heating means for thecathode element extending Within theV tubular cathode-supporting memberand including wires extending through the outer end sealing means forthe said member.

3. In a space discharge device incorporating at least diode elements, anenvelope formed of insulating material, a pair of rigid conductivetubular members projecting intosaid envelope and being ysealed into thewall thereof with their longitudinal axes in substantial alignment, saidmembers having their inner ends in predetermined spaced relation withinsaid envelope and having their outer end portions extending asubstantial distance outside the envelope, anode and cathode elementsdisposed within and extending from the respective inner end portions ofsaid members, said elements being of hollowcylindrical form and beingarranged coaxially with said members and having inner end surfaces inpredetermined spaced relation, means securing said elements to the innerends of said members, and means sealing the outer ends of said members.

4. In a space discharge device incorporating at least diode elements, anenvelope formed of insulating material, a pair of rigid conductivetubular members projecting into said envelope and being sealed into thewall thereof with their longitudinal axes in substantial alignment, saidmem` bers having their inner ends in predetermined spaced relationWithin said envelope and having their outer end portions extending asubstantial distance outside the envelope, tubular anode and cathodeelements of relatively small diameter extending i'rom therespectiveyinner end portions of said members substantially in axialalignment and in coaxial relation with said members, said elementshaving inner end surfaces in predetermined spaced relation, supportingmeans for said elements extending between the outer walls of saidelements andthe inner ends of said members, and means sealing the outerends of said members.

5. In a space discharge device incorporating at least diode elements, anenvelope formed of insulating material, a pair ol' rigid conductivetubular members projecting into said envelope and being sealed into thewall thereof with their longitudinal axes in substantial alignment, saidmembers having their inner ends in predetermined spaced relation withinsaid envelope and having their outer end portions extending asubstantial distance outside the envelope, tubular anode and cathodeelements of relatively small diameter extending from the respectiveinner end portions of said members substantially in axial alignment 10through the outer end sealing means therefor.

HARRY BRAN SON.

